Electric vehicles and other portable electronic devices typically employ rechargeable batteries to store energy (i.e., charge) when connected to mains electricity and output energy (i.e., discharge) for operation when not connected to mains electricity. Often, multiple batteries (referred to as battery cells) are electrically connected to form a battery pack that provides greater electrical characteristics (e.g., voltage, charge capacity, power density, etc.) than any of the battery cells individually.
Notably, however, the manner in which each battery cell within the battery pack is charged and discharged will impact the electrical properties of the cell as well as the battery pack as a whole. For example, operating a battery cell out of its design tolerances during charging or discharging can result in temporary or permanent loss of charge storage capacity and, if prolonged, can ultimately lead to failure of the cell. In the event that one or more electrical characteristics of a battery cell become reduced compared to other battery cells, this weak cell can raise safety and reliability issues within the battery pack, such as overcharge or under-discharge. Furthermore, when the battery cells are charged or discharged intermittently, rather than continuously over a majority of their service life, it becomes more difficult to keep the cells within tolerance.
Accordingly, there is ongoing interest in improved energy storage and delivery systems that are capable of charging and discharging batteries in a manner that maintains battery charge storage capacity and avoids or mitigates battery failure.